This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application entitled Tension Mask Frame Assembly for Color Cathode Ray Tube earlier filed in the Korean Industrial Property Office on Nov. 25, 2000, and there duly assigned Ser. No. 2000-70632 by that Office.
1. Field of the Invention
The present invention relates to color cathode-ray tubes, and more particularly, to a tension mask frame assembly for a color cathode-ray tube, having an improved structure capable of attenuating the vibrations of a tension mask supported by a frame.
2. Description of the Background Art
A color cathode-ray tube includes three electron beams emitted from an electron gun installed on a neck portion of a funnel and land on the red, green and blue fluorescent materials on a fluorescent film formed on the inner surface of a panel sealed by the funnel, through electron beam pass holes in a mask having a color distinction function, and excite the fluorescent materials, whereby a picture is formed.
Color cathode-ray tubes as described above pursue a flat screen surface to widen the viewing angle of viewers and prevent distortion of pictures, which requires flattening of a mask that is installed within a cathode-ray tube and performs a color distinction function. This mask becomes an obstacle in manufacturing completely-flat cathode-ray tubes.
A general tension mask frame assembly includes a frame and a flat tension mask. The frame has first and second support members that are parallel, and first and second elastic members, the ends of which are secured to the first support member and the second support member, to maintain an equal distance between the first and second support members. The flat tension mask has the facing longer sides welded to the first and second support members so that tension is applied to the first and second support members. The tension mask is made up of a slotted portion in which a plurality of electron beam pass holes are formed and a non-slotted portion extending from the edge of the slotted portion.
In this tension mask frame assembly, only the longer sides of the non-slotted portion of the tension mask are secured to the first and second support members, so that the shorter sides of the tension mask are free in direction Y perpendicular to the length direction X, that is, in a vertical direction with respect to one side of the tension mask. Thus, the tension mask supported by the frame is vibrated by external impacts or the sound pressure of a speaker, which causes mislanding that electron beams do not accurately land on a fluorescent film. Mislanding causes light emitting from a wrong fluorescent material by electron beams, resulting in a picture having a non-uniform resolution. In particular, since the inside of a cathode-ray tube is a vacuum, the vibration of a mask lasts for a long duration because of the lack of the resistance of air. Thus, a damper operation to rapidly vanish vibrations by changing vibration energy into another type of energy is required.
Exemplars of the art are U.S. Pat. No. 4,942,332 issued to Adler et al. for Tied Slit Mask for Color Cathode Ray Tubes disclosing a slit-typed tension mask, and U.S. Pat. No. 5,111,107 issued to Kume et al for Grid Apparatus for a Color Cathode Ray Tube which Eliminates Vibration of the Grids disclosing a tension mask frame assembly.
A conventional tension mask frame assembly by which vibrations are reduced using this damper operation is disclosed on Japanese Patent Publication No. 2000-77007 by Suzuki for Color Cathode-ray Tube. In a seventh tension mask resonance mode or below, this tension mask frame assembly has a structure in which the amplitude of the shorter side of a tension mask is relatively constant to the amplitude of the center of the tension mask, and vibrations are reduced by fastening a non-slotted portion at the shorter side of the tension mask with clips or rings.
It is therefore an objective of the present invention to provide a tension mask frame assembly for a color cathode-ray tube, that can increase the vibration attenuation effect by attenuating the vibration energy generated by non-elastic collision at the edge of the end of a tension mask supported by a frame, and can prevent picture jitter and improve the resolution by preventing mislanding of electron beams on a fluorescent film.
It is another object to have an increased stability in the picture quality of a cathode-ray tube.
It is yet another object to have a tension mask and a tension mask frame assembly that increase the stability of the picture without increasing the complexity and cost of manufacturing a cathode-ray tube.
It is still yet another object to have a cathode-ray tube that reduces vibration in a tension mask and yet be easy to manufacture.
To achieve the above objectives, the present invention provides a tension mask frame assembly for a color cathode-ray tube, including a tension mask having a slotted portion in which a plurality of electron beam passing holes are formed and a non-slotted portion located on the edge of the slotted portion, a frame for supporting two facing sides of the tension mask to apply a tensile force to the tension mask, and a vibration prevention unit including a damper having first and second attenuation portions that are maintained at a predetermined angle to form an insertion portion into which the edges of the tension mask not supported by the frame are inserted, and a support member for suspending the damper from the edges of the tension mask by passing through the first and second attenuation portions and the edges of the tension mask inserted into the insertion portion formed by the first and second attenuation portions.
In the tension mask frame assembly, the damper is formed by folding a plate-shaped member. The inner surface of each of the first and second attenuation portions linearly contact the end of the non-slotted portion of the tension mask. The insertion portion becomes narrower from its entrance toward its inside. A folded portion close to both side surfaces of the non-slotted portion is formed by folding the ends of the first and second attenuation portions at the side through which the non-slotted portion of the tension mask is inserted, in opposite directions.
The present invention also provides a tension mask frame assembly for a color cathode-ray tube, including a frame including first and second support members isolated from each other at a predetermined interval and at least a pair of elastic members, the ends of which are secured to the first and second support members, for supporting the first and second support members, a tension mask having a plurality of strips isolated from each other at a predetermined interval for forming slots and a plurality of real bridges installed between adjacent strips for partitioning a slot by connecting the adjacent strips to each other, where the longer sides of the tension mask perpendicular to the length direction of the strips are supported by the first and second support members such that a tensile force is applied to the plurality of strips, and a vibration prevention unit including a damper having first and second attenuation portions located at both sides of the edge of the tension mask for forming an insertion portion into which the edge of the tension mask is inserted, and at least one support member for suspending the damper from a non-slotted portion of the tension mask inserted into the insertion portion by passing through the first and second attenuation portions and the non-slotted portion.